<source lang = "xml">
<controls:EvalExpression x:Key="FilterExpression" Expression="(INPUT==null||INPUT=="") ? "true==true" : EXP " Context="{Binding}">
<controls:EvalExpressionParameter Name="EXP" Value="{Binding Source={x:Reference DateString}, Path=Text, Converter={StaticResource StringFormat}, ConverterParameter='Item.PropertyItems["DATE"].Value.ToString("yyyy/MM/dd").CompareTo("{0}")!="-1"'}" /> <controls:EvalExpressionParameter Name="INPUT" Value="{Binding Source={x:Reference DateString}, Path=Text}" />
</controls:EvalExpression>
</source>
<source lang = "xml">
<controls:EvalExpression x:Key="FilterExpression" Expression="(INPUT==null||INPUT=="") ? "true==true" : EXP " Context="{Binding}">
<controls:EvalExpressionParameter Name="EXP" Value="{Binding Source={x:Reference DateString}, Path=Text, Converter={StaticResource StringFormat}, ConverterParameter='Item.PropertyItems["DATE"].Value.ToString("yyyy/MM/dd").CompareTo("{0}")!="1"'}" /> <controls:EvalExpressionParameter Name="INPUT" Value="{Binding Source={x:Reference DateString}, Path=Text}" />
</controls:EvalExpression>
</source>